Romantic breakups in late adolescence and young adulthood are associated with a variety of poor mental health outcomes;thus, understanding the mechanisms that promote adaptive change is a timely endeavor. The proposed research addresses gaps in the existing literature by investigating the social context of emotional adjustment. Using an internet-based 28-day repeated sampling strategy;this goal will be achieved by way of a single proposed study involving 200 young adults (ages 18-25) who have experienced a recent, stressful romantic breakup. Previous literature has established an association between contact with an ex-partner and poorer outcomes, but few studies have attempted to explain this association. The first aim of the proposed research is to better understand this process by examining lead- lag associations between contact and emotional distress, as well as the impact of different types of contact on distress. Two mechanisms, longing and rumination, are proposed as mediators of the observed contact- distress association. Additionally, as longing and rumination may work in tandem, a path analysis model is hypothesized. The second aim of this research is to empirically investigate reactivity in measurement effects that occur as a byproduct of repeated assessment and Informant reports. The proposed research will divide the study sample into three experimental groups in order to examine the influence of daily reports of emotion and informant reports on on-going emotional adjustment. One group will provide only pre-adjustment (at entry into the study) and post-adjustment (28-days later) mood reports, the second group will provide a daily diary report of their moods, and a final group will provide a daily dairy report of their mood and have an informant report on their ongoing adjustment. The final aim is to examine individual profiles associated with recovery from a social loss. Data analysis will occur in a multilevel modeling framework using linear and non-linear models, lower-level mediation, and path analysis. PUBLIC HEALTH RELEVANCE: Social losses are among life's most distressing experience. The proposed research investigates (using novel internet data collection procedures) how young adults come to terms of a stressful romantic breakup experience. The studies focus on an aspect of the social environment-contact with an ex-partner-that may be particularly useful for understanding who fares well or poorly in the face of this stressful life event. The findings from this research will have broad implications for understanding how people emotionally recover from social upheavals and illustrate new ways of studying adjustment over time. Pinpointing these mechanisms of change can ultimately inform preventative and therapeutic interventions.